What is the frequency for inspection of electrical boxes and is it an OSHA regulation?

There are no specific requirements for inspection of electrical boxes. However, just the proper installation and maintenance of electrical boxes should keep them in the proper shape to prevent hazards to employees. The following references to inspection imply that inspections should be done.

Section 1910.303(g)(1)(ii) — Clear spaces: Working space required by this subpart may not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.

Section 1910.308(a)(2)(iii) — A means shall be provided to completely isolate equipment for inspection and repairs. Isolating means which are not designed to interrupt the load current of the circuit shall be either interlocked with an approved circuit interrupter or provided with a sign warning against opening them under load.

There are inspection requirements in the lockout/tagout, portable equipment (power tools/extension cords), and PPE section of the electrical requirements but these do not relate to electrical boxes.